1. Field of the Invention
This invention pertains to the attachment of the zipper in a direction transverse to the film in a form fill and seal machine, wherein the edges of the zipper are not attached to the film prior to the film turning down from the forming collar.
2. Description of the Prior Art
In the prior art of a form fill and seal (FFS) method and apparatus, it is known to attach the zipper in a transverse direction prior to the film turning down from the forming collar. However, there is a tendency for twisting and tension of the zipper as the zipper makes the drastic change of direction from flat to conforming to the diameter of the fill tube as the film turns down from the forming collar. This can result in degraded alignment of the zipper. These deficiencies of the prior art are illustrated in FIGS. 2A and 3A. Related prior art includes U.S. Pat. No. 6,017,412 entitled xe2x80x9cMethod for Attaching Reclosable Zipper Strip Transversely to Thermoplastic Film Materialxe2x80x9d issued on Jan. 25, 2000 to Van Erden et al. and U.S. patent application Ser. No. 09/234,174 entitled xe2x80x9cTransverse Direction Zipper Attaching Apparatus and Methodxe2x80x9d filed on Jan. 19, 1999.
It is therefore an object of the present invention to reduce the twisting and tension of the transverse directed zipper in a form fill and seal method and apparatus as the film turns down from the forming collar.
It is therefore a further object of the present invention to reduce the twisting and tension of the transverse directed zipper in a form fill and seal method and apparatus as the zipper on the film makes the change of direction from flat to conforming to the diameter of the fill tube.
It is therefore a still further object of the present invention to provide for improved alignment of the zipper in a form fill and seal apparatus.
These and other objects are attained by securing the zipper transversely to the film at a central portion of the zipper while leaving the ends of the zipper free prior to turning the film down from the forming collar and making the change of direction from flat to conforming to the diameter of the fill tube. This allows the zipper to remain in a more natural or relaxed shape during this transition providing for improved alignment of the zipper.